(a) Field of the Invention
The present invention relates to an automatic transmission of a vehicle, and more particularly, the present invention relates to an automatic transmission with reduced overall length, weight and manufacturing cost thereof.
(b) Description
Generally, an automatic transmission is an apparatus that automatically operates a clutch and a transmission by a machine rather than a human. It rotates wheels by automatically changing rotation speed and torque created in an engine.
Particularly, as shown in FIG. 1, such an automatic transmission includes a case 10 forming an exterior of the automatic transmission and a planetary gear set 20 in the case 10. Furthermore, the planetary gear set 20 includes a sun gear 21, a plurality of pinions 23, and a ring gear 25.
In more detail, the sun gear 21 is included at an exterior circumference of a rotating shaft S. A plurality of pinions 23 are supported by a carrier (not shown in FIG. 1). and engaged with an exterior circumference of the sun gear 21, and rotated along the exterior circumference of the sun gear 21. An interior circumference of the ring gear 25 is engaged with an exterior circumference of a plurality of pinion 23, and the ring gear 25 is rotated along the exterior circumference of a plurality of pinion 23. Accordingly, when one among the sun gear 21, carrier (not shown), and ring gear 25 is fixed, rotation speed and torque transmitted to en output shaft (not shown) can be changed.
As shown in FIG 1, conventional automatic transmissions have a ring gear 25 rotatably supported around a rotating shaft S.
The ring gear 25 is rotatably supported and it needs to be prevented from moving in an axial direction. To address this problem, conventional automatic transmissions have been designed to have a structure wherein a thrust bearing 40 located around the rotating shaft S is mounted to a support flange 30 protruded from the lateral side of the ring gear 25. Particularly, the support flange 30 has a shape that is bent several times and convexes into the right in the drawings in order to prevent interferences between the support flange 30 and other components in the ring gear 25, such as the planetary gear set.
However, although the structural configuration above can prevent the axial movement of ring gear 25, it causes overall length of the automatic transmission to be longer, thereby increasing its overall weight and manufacturing cost.
There is thus still a need for an automatic transmission with reduced overall length, weight and manufacturing cost.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.